drivers/block/ublk_drv.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Userspace block device - block device which IO is handled from userspace
   4  *
   5  * Take full use of io_uring passthrough command for communicating with
   6  * ublk userspace daemon(ublksrvd) for handling basic IO request.
   7  *
   8  * Copyright 2022 Ming Lei <ming.lei@redhat.com>
   9  *
  10  * (part of code stolen from loop.c)
  11  */
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/sched.h>
  15 #include <linux/fs.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/file.h>
  18 #include <linux/stat.h>
  19 #include <linux/errno.h>
  20 #include <linux/major.h>
  21 #include <linux/wait.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/init.h>
  24 #include <linux/swap.h>
  25 #include <linux/slab.h>
  26 #include <linux/compat.h>
  27 #include <linux/mutex.h>
  28 #include <linux/writeback.h>
  29 #include <linux/completion.h>
  30 #include <linux/highmem.h>
  31 #include <linux/sysfs.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/falloc.h>
  34 #include <linux/uio.h>
  35 #include <linux/ioprio.h>
  36 #include <linux/sched/mm.h>
  37 #include <linux/uaccess.h>
  38 #include <linux/cdev.h>
  39 #include <linux/io_uring.h>
  40 #include <linux/blk-mq.h>
  41 #include <linux/delay.h>
  42 #include <linux/mm.h>
  43 #include <asm/page.h>
  44 #include <linux/task_work.h>
  45 #include <linux/namei.h>
  46 #include <uapi/linux/ublk_cmd.h>
  47
  48 #define UBLK_MINORS             (1U << MINORBITS)
  49
  50 /* All UBLK_F_* have to be included into UBLK_F_ALL */
  51 #define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY \
  52                 | UBLK_F_URING_CMD_COMP_IN_TASK \
  53                 | UBLK_F_NEED_GET_DATA \
  54                 | UBLK_F_USER_RECOVERY \
  55                 | UBLK_F_USER_RECOVERY_REISSUE \
  56                 | UBLK_F_UNPRIVILEGED_DEV \
  57                 | UBLK_F_CMD_IOCTL_ENCODE)
  58
  59 /* All UBLK_PARAM_TYPE_* should be included here */
  60 #define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | \
  61                 UBLK_PARAM_TYPE_DISCARD | UBLK_PARAM_TYPE_DEVT)
  62
  63 struct ublk_rq_data {
  64         struct llist_node node;
  65 };
  66
  67 struct ublk_uring_cmd_pdu {
  68         struct ublk_queue *ubq;
  69 };
  70
  71 /*
  72  * io command is active: sqe cmd is received, and its cqe isn't done
  73  *
  74  * If the flag is set, the io command is owned by ublk driver, and waited
  75  * for incoming blk-mq request from the ublk block device.
  76  *
  77  * If the flag is cleared, the io command will be completed, and owned by
  78  * ublk server.
  79  */
  80 #define UBLK_IO_FLAG_ACTIVE     0x01
  81
  82 /*
  83  * IO command is completed via cqe, and it is being handled by ublksrv, and
  84  * not committed yet
  85  *
  86  * Basically exclusively with UBLK_IO_FLAG_ACTIVE, so can be served for
  87  * cross verification
  88  */
  89 #define UBLK_IO_FLAG_OWNED_BY_SRV 0x02
  90
  91 /*
  92  * IO command is aborted, so this flag is set in case of
  93  * !UBLK_IO_FLAG_ACTIVE.
  94  *
  95  * After this flag is observed, any pending or new incoming request
  96  * associated with this io command will be failed immediately
  97  */
  98 #define UBLK_IO_FLAG_ABORTED 0x04
  99
 100 /*
 101  * UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires
 102  * get data buffer address from ublksrv.
 103  *
 104  * Then, bio data could be copied into this data buffer for a WRITE request
 105  * after the IO command is issued again and UBLK_IO_FLAG_NEED_GET_DATA is unset.
 106  */
 107 #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
 108
 109 struct ublk_io {
 110         /* userspace buffer address from io cmd */
 111         __u64   addr;
 112         unsigned int flags;
 113         int res;
 114
 115         struct io_uring_cmd *cmd;
 116 };
 117
 118 struct ublk_queue {
 119         int q_id;
 120         int q_depth;
 121
 122         unsigned long flags;
 123         struct task_struct      *ubq_daemon;
 124         char *io_cmd_buf;
 125
 126         struct llist_head       io_cmds;
 127
 128         unsigned long io_addr;  /* mapped vm address */
 129         unsigned int max_io_sz;
 130         bool force_abort;
 131         bool timeout;
 132         unsigned short nr_io_ready;     /* how many ios setup */
 133         struct ublk_device *dev;
 134         struct ublk_io ios[];
 135 };
 136
 137 #define UBLK_DAEMON_MONITOR_PERIOD      (5 * HZ)
 138
 139 struct ublk_device {
 140         struct gendisk          *ub_disk;
 141
 142         char    *__queues;
 143
 144         unsigned int    queue_size;
 145         struct ublksrv_ctrl_dev_info    dev_info;
 146
 147         struct blk_mq_tag_set   tag_set;
 148
 149         struct cdev             cdev;
 150         struct device           cdev_dev;
 151
 152 #define UB_STATE_OPEN           0
 153 #define UB_STATE_USED           1
 154 #define UB_STATE_DELETED        2
 155         unsigned long           state;
 156         int                     ub_number;
 157
 158         struct mutex            mutex;
 159
 160         spinlock_t              mm_lock;
 161         struct mm_struct        *mm;
 162
 163         struct ublk_params      params;
 164
 165         struct completion       completion;
 166         unsigned int            nr_queues_ready;
 167         unsigned int            nr_privileged_daemon;
 168
 169         /*
 170          * Our ubq->daemon may be killed without any notification, so
 171          * monitor each queue's daemon periodically
 172          */
 173         struct delayed_work     monitor_work;
 174         struct work_struct      quiesce_work;
 175         struct work_struct      stop_work;
 176 };
 177
 178 /* header of ublk_params */
 179 struct ublk_params_header {
 180         __u32   len;
 181         __u32   types;
 182 };
 183
 184 static dev_t ublk_chr_devt;
 185 static struct class *ublk_chr_class;
 186
 187 static DEFINE_IDR(ublk_index_idr);
 188 static DEFINE_SPINLOCK(ublk_idr_lock);
 189 static wait_queue_head_t ublk_idr_wq;   /* wait until one idr is freed */
 190
 191 static DEFINE_MUTEX(ublk_ctl_mutex);
 192
 193 /*
 194  * Max ublk devices allowed to add
 195  *
 196  * It can be extended to one per-user limit in future or even controlled
 197  * by cgroup.
 198  */
 199 static unsigned int ublks_max = 64;
 200 static unsigned int ublks_added;        /* protected by ublk_ctl_mutex */
 201
 202 static struct miscdevice ublk_misc;
 203
 204 static void ublk_dev_param_basic_apply(struct ublk_device *ub)
 205 {
 206         struct request_queue *q = ub->ub_disk->queue;
 207         const struct ublk_param_basic *p = &ub->params.basic;
 208
 209         blk_queue_logical_block_size(q, 1 << p->logical_bs_shift);
 210         blk_queue_physical_block_size(q, 1 << p->physical_bs_shift);
 211         blk_queue_io_min(q, 1 << p->io_min_shift);
 212         blk_queue_io_opt(q, 1 << p->io_opt_shift);
 213
 214         blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
 215                         p->attrs & UBLK_ATTR_FUA);
 216         if (p->attrs & UBLK_ATTR_ROTATIONAL)
 217                 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
 218         else
 219                 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
 220
 221         blk_queue_max_hw_sectors(q, p->max_sectors);
 222         blk_queue_chunk_sectors(q, p->chunk_sectors);
 223         blk_queue_virt_boundary(q, p->virt_boundary_mask);
 224
 225         if (p->attrs & UBLK_ATTR_READ_ONLY)
 226                 set_disk_ro(ub->ub_disk, true);
 227
 228         set_capacity(ub->ub_disk, p->dev_sectors);
 229 }
 230
 231 static void ublk_dev_param_discard_apply(struct ublk_device *ub)
 232 {
 233         struct request_queue *q = ub->ub_disk->queue;
 234         const struct ublk_param_discard *p = &ub->params.discard;
 235
 236         q->limits.discard_alignment = p->discard_alignment;
 237         q->limits.discard_granularity = p->discard_granularity;
 238         blk_queue_max_discard_sectors(q, p->max_discard_sectors);
 239         blk_queue_max_write_zeroes_sectors(q,
 240                         p->max_write_zeroes_sectors);
 241         blk_queue_max_discard_segments(q, p->max_discard_segments);
 242 }
 243
 244 static int ublk_validate_params(const struct ublk_device *ub)
 245 {
 246         /* basic param is the only one which must be set */
 247         if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
 248                 const struct ublk_param_basic *p = &ub->params.basic;
 249
 250                 if (p->logical_bs_shift > PAGE_SHIFT || p->logical_bs_shift < 9)
 251                         return -EINVAL;
 252
 253                 if (p->logical_bs_shift > p->physical_bs_shift)
 254                         return -EINVAL;
 255
 256                 if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
 257                         return -EINVAL;
 258         } else
 259                 return -EINVAL;
 260
 261         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD) {
 262                 const struct ublk_param_discard *p = &ub->params.discard;
 263
 264                 /* So far, only support single segment discard */
 265                 if (p->max_discard_sectors && p->max_discard_segments != 1)
 266                         return -EINVAL;
 267
 268                 if (!p->discard_granularity)
 269                         return -EINVAL;
 270         }
 271
 272         /* dev_t is read-only */
 273         if (ub->params.types & UBLK_PARAM_TYPE_DEVT)
 274                 return -EINVAL;
 275
 276         return 0;
 277 }
 278
 279 static int ublk_apply_params(struct ublk_device *ub)
 280 {
 281         if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
 282                 return -EINVAL;
 283
 284         ublk_dev_param_basic_apply(ub);
 285
 286         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
 287                 ublk_dev_param_discard_apply(ub);
 288
 289         return 0;
 290 }
 291
 292 static inline bool ublk_need_get_data(const struct ublk_queue *ubq)
 293 {
 294         return ubq->flags & UBLK_F_NEED_GET_DATA;
 295 }
 296
 297 static struct ublk_device *ublk_get_device(struct ublk_device *ub)
 298 {
 299         if (kobject_get_unless_zero(&ub->cdev_dev.kobj))
 300                 return ub;
 301         return NULL;
 302 }
 303
 304 static void ublk_put_device(struct ublk_device *ub)
 305 {
 306         put_device(&ub->cdev_dev);
 307 }
 308
 309 static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev,
 310                 int qid)
 311 {
 312        return (struct ublk_queue *)&(dev->__queues[qid * dev->queue_size]);
 313 }
 314
 315 static inline bool ublk_rq_has_data(const struct request *rq)
 316 {
 317         return bio_has_data(rq->bio);
 318 }
 319
 320 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 321                 int tag)
 322 {
 323         return (struct ublksrv_io_desc *)
 324                 &(ubq->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]);
 325 }
 326
 327 static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
 328 {
 329         return ublk_get_queue(ub, q_id)->io_cmd_buf;
 330 }
 331
 332 static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
 333 {
 334         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 335
 336         return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc),
 337                         PAGE_SIZE);
 338 }
 339
 340 static inline bool ublk_queue_can_use_recovery_reissue(
 341                 struct ublk_queue *ubq)
 342 {
 343         return (ubq->flags & UBLK_F_USER_RECOVERY) &&
 344                         (ubq->flags & UBLK_F_USER_RECOVERY_REISSUE);
 345 }
 346
 347 static inline bool ublk_queue_can_use_recovery(
 348                 struct ublk_queue *ubq)
 349 {
 350         return ubq->flags & UBLK_F_USER_RECOVERY;
 351 }
 352
 353 static inline bool ublk_can_use_recovery(struct ublk_device *ub)
 354 {
 355         return ub->dev_info.flags & UBLK_F_USER_RECOVERY;
 356 }
 357
 358 static void ublk_free_disk(struct gendisk *disk)
 359 {
 360         struct ublk_device *ub = disk->private_data;
 361
 362         clear_bit(UB_STATE_USED, &ub->state);
 363         put_device(&ub->cdev_dev);
 364 }
 365
 366 static void ublk_store_owner_uid_gid(unsigned int *owner_uid,
 367                 unsigned int *owner_gid)
 368 {
 369         kuid_t uid;
 370         kgid_t gid;
 371
 372         current_uid_gid(&uid, &gid);
 373
 374         *owner_uid = from_kuid(&init_user_ns, uid);
 375         *owner_gid = from_kgid(&init_user_ns, gid);
 376 }
 377
 378 static int ublk_open(struct block_device *bdev, fmode_t mode)
 379 {
 380         struct ublk_device *ub = bdev->bd_disk->private_data;
 381
 382         if (capable(CAP_SYS_ADMIN))
 383                 return 0;
 384
 385         /*
 386          * If it is one unprivileged device, only owner can open
 387          * the disk. Otherwise it could be one trap made by one
 388          * evil user who grants this disk's privileges to other
 389          * users deliberately.
 390          *
 391          * This way is reasonable too given anyone can create
 392          * unprivileged device, and no need other's grant.
 393          */
 394         if (ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV) {
 395                 unsigned int curr_uid, curr_gid;
 396
 397                 ublk_store_owner_uid_gid(&curr_uid, &curr_gid);
 398
 399                 if (curr_uid != ub->dev_info.owner_uid || curr_gid !=
 400                                 ub->dev_info.owner_gid)
 401                         return -EPERM;
 402         }
 403
 404         return 0;
 405 }
 406
 407 static const struct block_device_operations ub_fops = {
 408         .owner =        THIS_MODULE,
 409         .open =         ublk_open,
 410         .free_disk =    ublk_free_disk,
 411 };
 412
 413 #define UBLK_MAX_PIN_PAGES      32
 414
 415 struct ublk_map_data {
 416         const struct request *rq;
 417         unsigned long   ubuf;
 418         unsigned int    len;
 419 };
 420
 421 struct ublk_io_iter {
 422         struct page *pages[UBLK_MAX_PIN_PAGES];
 423         unsigned pg_off;        /* offset in the 1st page in pages */
 424         int nr_pages;           /* how many page pointers in pages */
 425         struct bio *bio;
 426         struct bvec_iter iter;
 427 };
 428
 429 static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data,
 430                 unsigned max_bytes, bool to_vm)
 431 {
 432         const unsigned total = min_t(unsigned, max_bytes,
 433                         PAGE_SIZE - data->pg_off +
 434                         ((data->nr_pages - 1) << PAGE_SHIFT));
 435         unsigned done = 0;
 436         unsigned pg_idx = 0;
 437
 438         while (done < total) {
 439                 struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);
 440                 const unsigned int bytes = min3(bv.bv_len, total - done,
 441                                 (unsigned)(PAGE_SIZE - data->pg_off));
 442                 void *bv_buf = bvec_kmap_local(&bv);
 443                 void *pg_buf = kmap_local_page(data->pages[pg_idx]);
 444
 445                 if (to_vm)
 446                         memcpy(pg_buf + data->pg_off, bv_buf, bytes);
 447                 else
 448                         memcpy(bv_buf, pg_buf + data->pg_off, bytes);
 449
 450                 kunmap_local(pg_buf);
 451                 kunmap_local(bv_buf);
 452
 453                 /* advance page array */
 454                 data->pg_off += bytes;
 455                 if (data->pg_off == PAGE_SIZE) {
 456                         pg_idx += 1;
 457                         data->pg_off = 0;
 458                 }
 459
 460                 done += bytes;
 461
 462                 /* advance bio */
 463                 bio_advance_iter_single(data->bio, &data->iter, bytes);
 464                 if (!data->iter.bi_size) {
 465                         data->bio = data->bio->bi_next;
 466                         if (data->bio == NULL)
 467                                 break;
 468                         data->iter = data->bio->bi_iter;
 469                 }
 470         }
 471
 472         return done;
 473 }
 474
 475 static int ublk_copy_user_pages(struct ublk_map_data *data, bool to_vm)
 476 {
 477         const unsigned int gup_flags = to_vm ? FOLL_WRITE : 0;
 478         const unsigned long start_vm = data->ubuf;
 479         unsigned int done = 0;
 480         struct ublk_io_iter iter = {
 481                 .pg_off = start_vm & (PAGE_SIZE - 1),
 482                 .bio    = data->rq->bio,
 483                 .iter   = data->rq->bio->bi_iter,
 484         };
 485         const unsigned int nr_pages = round_up(data->len +
 486                         (start_vm & (PAGE_SIZE - 1)), PAGE_SIZE) >> PAGE_SHIFT;
 487
 488         while (done < nr_pages) {
 489                 const unsigned to_pin = min_t(unsigned, UBLK_MAX_PIN_PAGES,
 490                                 nr_pages - done);
 491                 unsigned i, len;
 492
 493                 iter.nr_pages = get_user_pages_fast(start_vm +
 494                                 (done << PAGE_SHIFT), to_pin, gup_flags,
 495                                 iter.pages);
 496                 if (iter.nr_pages <= 0)
 497                         return done == 0 ? iter.nr_pages : done;
 498                 len = ublk_copy_io_pages(&iter, data->len, to_vm);
 499                 for (i = 0; i < iter.nr_pages; i++) {
 500                         if (to_vm)
 501                                 set_page_dirty(iter.pages[i]);
 502                         put_page(iter.pages[i]);
 503                 }
 504                 data->len -= len;
 505                 done += iter.nr_pages;
 506         }
 507
 508         return done;
 509 }
 510
 511 static inline bool ublk_need_map_req(const struct request *req)
 512 {
 513         return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;
 514 }
 515
 516 static inline bool ublk_need_unmap_req(const struct request *req)
 517 {
 518         return ublk_rq_has_data(req) && req_op(req) == REQ_OP_READ;
 519 }
 520
 521 static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
 522                 struct ublk_io *io)
 523 {
 524         const unsigned int rq_bytes = blk_rq_bytes(req);
 525
 526         /*
 527          * no zero copy, we delay copy WRITE request data into ublksrv
 528          * context and the big benefit is that pinning pages in current
 529          * context is pretty fast, see ublk_pin_user_pages
 530          */
 531         if (ublk_need_map_req(req)) {
 532                 struct ublk_map_data data = {
 533                         .rq     =       req,
 534                         .ubuf   =       io->addr,
 535                         .len    =       rq_bytes,
 536                 };
 537
 538                 ublk_copy_user_pages(&data, true);
 539
 540                 return rq_bytes - data.len;
 541         }
 542         return rq_bytes;
 543 }
 544
 545 static int ublk_unmap_io(const struct ublk_queue *ubq,
 546                 const struct request *req,
 547                 struct ublk_io *io)
 548 {
 549         const unsigned int rq_bytes = blk_rq_bytes(req);
 550
 551         if (ublk_need_unmap_req(req)) {
 552                 struct ublk_map_data data = {
 553                         .rq     =       req,
 554                         .ubuf   =       io->addr,
 555                         .len    =       io->res,
 556                 };
 557
 558                 WARN_ON_ONCE(io->res > rq_bytes);
 559
 560                 ublk_copy_user_pages(&data, false);
 561
 562                 return io->res - data.len;
 563         }
 564         return rq_bytes;
 565 }
 566
 567 static inline unsigned int ublk_req_build_flags(struct request *req)
 568 {
 569         unsigned flags = 0;
 570
 571         if (req->cmd_flags & REQ_FAILFAST_DEV)
 572                 flags |= UBLK_IO_F_FAILFAST_DEV;
 573
 574         if (req->cmd_flags & REQ_FAILFAST_TRANSPORT)
 575                 flags |= UBLK_IO_F_FAILFAST_TRANSPORT;
 576
 577         if (req->cmd_flags & REQ_FAILFAST_DRIVER)
 578                 flags |= UBLK_IO_F_FAILFAST_DRIVER;
 579
 580         if (req->cmd_flags & REQ_META)
 581                 flags |= UBLK_IO_F_META;
 582
 583         if (req->cmd_flags & REQ_FUA)
 584                 flags |= UBLK_IO_F_FUA;
 585
 586         if (req->cmd_flags & REQ_NOUNMAP)
 587                 flags |= UBLK_IO_F_NOUNMAP;
 588
 589         if (req->cmd_flags & REQ_SWAP)
 590                 flags |= UBLK_IO_F_SWAP;
 591
 592         return flags;
 593 }
 594
 595 static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 596 {
 597         struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 598         struct ublk_io *io = &ubq->ios[req->tag];
 599         u32 ublk_op;
 600
 601         switch (req_op(req)) {
 602         case REQ_OP_READ:
 603                 ublk_op = UBLK_IO_OP_READ;
 604                 break;
 605         case REQ_OP_WRITE:
 606                 ublk_op = UBLK_IO_OP_WRITE;
 607                 break;
 608         case REQ_OP_FLUSH:
 609                 ublk_op = UBLK_IO_OP_FLUSH;
 610                 break;
 611         case REQ_OP_DISCARD:
 612                 ublk_op = UBLK_IO_OP_DISCARD;
 613                 break;
 614         case REQ_OP_WRITE_ZEROES:
 615                 ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 616                 break;
 617         default:
 618                 return BLK_STS_IOERR;
 619         }
 620
 621         /* need to translate since kernel may change */
 622         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 623         iod->nr_sectors = blk_rq_sectors(req);
 624         iod->start_sector = blk_rq_pos(req);
 625         iod->addr = io->addr;
 626
 627         return BLK_STS_OK;
 628 }
 629
 630 static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 631                 struct io_uring_cmd *ioucmd)
 632 {
 633         return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu;
 634 }
 635
 636 static inline bool ubq_daemon_is_dying(struct ublk_queue *ubq)
 637 {
 638         return ubq->ubq_daemon->flags & PF_EXITING;
 639 }
 640
 641 /* todo: handle partial completion */
 642 static void ublk_complete_rq(struct request *req)
 643 {
 644         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 645         struct ublk_io *io = &ubq->ios[req->tag];
 646         unsigned int unmapped_bytes;
 647         blk_status_t res = BLK_STS_OK;
 648
 649         /* failed read IO if nothing is read */
 650         if (!io->res && req_op(req) == REQ_OP_READ)
 651                 io->res = -EIO;
 652
 653         if (io->res < 0) {
 654                 res = errno_to_blk_status(io->res);
 655                 goto exit;
 656         }
 657
 658         /*
 659          * FLUSH, DISCARD or WRITE_ZEROES usually won't return bytes returned, so end them
 660          * directly.
 661          *
 662          * Both the two needn't unmap.
 663          */
 664         if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE)
 665                 goto exit;
 666
 667         /* for READ request, writing data in iod->addr to rq buffers */
 668         unmapped_bytes = ublk_unmap_io(ubq, req, io);
 669
 670         /*
 671          * Extremely impossible since we got data filled in just before
 672          *
 673          * Re-read simply for this unlikely case.
 674          */
 675         if (unlikely(unmapped_bytes < io->res))
 676                 io->res = unmapped_bytes;
 677
 678         if (blk_update_request(req, BLK_STS_OK, io->res))
 679                 blk_mq_requeue_request(req, true);
 680         else
 681                 __blk_mq_end_request(req, BLK_STS_OK);
 682
 683         return;
 684 exit:
 685         blk_mq_end_request(req, res);
 686 }
 687
 688 /*
 689  * Since __ublk_rq_task_work always fails requests immediately during
 690  * exiting, __ublk_fail_req() is only called from abort context during
 691  * exiting. So lock is unnecessary.
 692  *
 693  * Also aborting may not be started yet, keep in mind that one failed
 694  * request may be issued by block layer again.
 695  */
 696 static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
 697                 struct request *req)
 698 {
 699         WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
 700
 701         if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
 702                 io->flags |= UBLK_IO_FLAG_ABORTED;
 703                 if (ublk_queue_can_use_recovery_reissue(ubq))
 704                         blk_mq_requeue_request(req, false);
 705                 else
 706                         blk_mq_end_request(req, BLK_STS_IOERR);
 707         }
 708 }
 709
 710 static void ubq_complete_io_cmd(struct ublk_io *io, int res,
 711                                 unsigned issue_flags)
 712 {
 713         /* mark this cmd owned by ublksrv */
 714         io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV;
 715
 716         /*
 717          * clear ACTIVE since we are done with this sqe/cmd slot
 718          * We can only accept io cmd in case of being not active.
 719          */
 720         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
 721
 722         /* tell ublksrv one io request is coming */
 723         io_uring_cmd_done(io->cmd, res, 0, issue_flags);
 724 }
 725
 726 #define UBLK_REQUEUE_DELAY_MS   3
 727
 728 static inline void __ublk_abort_rq(struct ublk_queue *ubq,
 729                 struct request *rq)
 730 {
 731         /* We cannot process this rq so just requeue it. */
 732         if (ublk_queue_can_use_recovery(ubq))
 733                 blk_mq_requeue_request(rq, false);
 734         else
 735                 blk_mq_end_request(rq, BLK_STS_IOERR);
 736
 737         mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
 738 }
 739
 740 static inline void __ublk_rq_task_work(struct request *req,
 741                                        unsigned issue_flags)
 742 {
 743         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 744         int tag = req->tag;
 745         struct ublk_io *io = &ubq->ios[tag];
 746         unsigned int mapped_bytes;
 747
 748         pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",
 749                         __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 750                         ublk_get_iod(ubq, req->tag)->addr);
 751
 752         /*
 753          * Task is exiting if either:
 754          *
 755          * (1) current != ubq_daemon.
 756          * io_uring_cmd_complete_in_task() tries to run task_work
 757          * in a workqueue if ubq_daemon(cmd's task) is PF_EXITING.
 758          *
 759          * (2) current->flags & PF_EXITING.
 760          */
 761         if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {
 762                 __ublk_abort_rq(ubq, req);
 763                 return;
 764         }
 765
 766         if (ublk_need_get_data(ubq) && ublk_need_map_req(req)) {
 767                 /*
 768                  * We have not handled UBLK_IO_NEED_GET_DATA command yet,
 769                  * so immepdately pass UBLK_IO_RES_NEED_GET_DATA to ublksrv
 770                  * and notify it.
 771                  */
 772                 if (!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) {
 773                         io->flags |= UBLK_IO_FLAG_NEED_GET_DATA;
 774                         pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n",
 775                                         __func__, io->cmd->cmd_op, ubq->q_id,
 776                                         req->tag, io->flags);
 777                         ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA, issue_flags);
 778                         return;
 779                 }
 780                 /*
 781                  * We have handled UBLK_IO_NEED_GET_DATA command,
 782                  * so clear UBLK_IO_FLAG_NEED_GET_DATA now and just
 783                  * do the copy work.
 784                  */
 785                 io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
 786                 /* update iod->addr because ublksrv may have passed a new io buffer */
 787                 ublk_get_iod(ubq, req->tag)->addr = io->addr;
 788                 pr_devel("%s: update iod->addr: op %d, qid %d tag %d io_flags %x addr %llx\n",
 789                                 __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 790                                 ublk_get_iod(ubq, req->tag)->addr);
 791         }
 792
 793         mapped_bytes = ublk_map_io(ubq, req, io);
 794
 795         /* partially mapped, update io descriptor */
 796         if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
 797                 /*
 798                  * Nothing mapped, retry until we succeed.
 799                  *
 800                  * We may never succeed in mapping any bytes here because
 801                  * of OOM. TODO: reserve one buffer with single page pinned
 802                  * for providing forward progress guarantee.
 803                  */
 804                 if (unlikely(!mapped_bytes)) {
 805                         blk_mq_requeue_request(req, false);
 806                         blk_mq_delay_kick_requeue_list(req->q,
 807                                         UBLK_REQUEUE_DELAY_MS);
 808                         return;
 809                 }
 810
 811                 ublk_get_iod(ubq, req->tag)->nr_sectors =
 812                         mapped_bytes >> 9;
 813         }
 814
 815         ubq_complete_io_cmd(io, UBLK_IO_RES_OK, issue_flags);
 816 }
 817
 818 static inline void ublk_forward_io_cmds(struct ublk_queue *ubq,
 819                                         unsigned issue_flags)
 820 {
 821         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 822         struct ublk_rq_data *data, *tmp;
 823
 824         io_cmds = llist_reverse_order(io_cmds);
 825         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 826                 __ublk_rq_task_work(blk_mq_rq_from_pdu(data), issue_flags);
 827 }
 828
 829 static inline void ublk_abort_io_cmds(struct ublk_queue *ubq)
 830 {
 831         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 832         struct ublk_rq_data *data, *tmp;
 833
 834         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 835                 __ublk_abort_rq(ubq, blk_mq_rq_from_pdu(data));
 836 }
 837
 838 static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd, unsigned issue_flags)
 839 {
 840         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 841         struct ublk_queue *ubq = pdu->ubq;
 842
 843         ublk_forward_io_cmds(ubq, issue_flags);
 844 }
 845
 846 static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)
 847 {
 848         struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
 849         struct ublk_io *io;
 850
 851         if (!llist_add(&data->node, &ubq->io_cmds))
 852                 return;
 853
 854         io = &ubq->ios[rq->tag];
 855         /*
 856          * If the check pass, we know that this is a re-issued request aborted
 857          * previously in monitor_work because the ubq_daemon(cmd's task) is
 858          * PF_EXITING. We cannot call io_uring_cmd_complete_in_task() anymore
 859          * because this ioucmd's io_uring context may be freed now if no inflight
 860          * ioucmd exists. Otherwise we may cause null-deref in ctx->fallback_work.
 861          *
 862          * Note: monitor_work sets UBLK_IO_FLAG_ABORTED and ends this request(releasing
 863          * the tag). Then the request is re-started(allocating the tag) and we are here.
 864          * Since releasing/allocating a tag implies smp_mb(), finding UBLK_IO_FLAG_ABORTED
 865          * guarantees that here is a re-issued request aborted previously.
 866          */
 867         if (unlikely(io->flags & UBLK_IO_FLAG_ABORTED)) {
 868                 ublk_abort_io_cmds(ubq);
 869         } else {
 870                 struct io_uring_cmd *cmd = io->cmd;
 871                 struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 872
 873                 pdu->ubq = ubq;
 874                 io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
 875         }
 876 }
 877
 878 static enum blk_eh_timer_return ublk_timeout(struct request *rq)
 879 {
 880         struct ublk_queue *ubq = rq->mq_hctx->driver_data;
 881
 882         if (ubq->flags & UBLK_F_UNPRIVILEGED_DEV) {
 883                 if (!ubq->timeout) {
 884                         send_sig(SIGKILL, ubq->ubq_daemon, 0);
 885                         ubq->timeout = true;
 886                 }
 887
 888                 return BLK_EH_DONE;
 889         }
 890
 891         return BLK_EH_RESET_TIMER;
 892 }
 893
 894 static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
 895                 const struct blk_mq_queue_data *bd)
 896 {
 897         struct ublk_queue *ubq = hctx->driver_data;
 898         struct request *rq = bd->rq;
 899         blk_status_t res;
 900
 901         /* fill iod to slot in io cmd buffer */
 902         res = ublk_setup_iod(ubq, rq);
 903         if (unlikely(res != BLK_STS_OK))
 904                 return BLK_STS_IOERR;
 905
 906         /* With recovery feature enabled, force_abort is set in
 907          * ublk_stop_dev() before calling del_gendisk(). We have to
 908          * abort all requeued and new rqs here to let del_gendisk()
 909          * move on. Besides, we cannot not call io_uring_cmd_complete_in_task()
 910          * to avoid UAF on io_uring ctx.
 911          *
 912          * Note: force_abort is guaranteed to be seen because it is set
 913          * before request queue is unqiuesced.
 914          */
 915         if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort))
 916                 return BLK_STS_IOERR;
 917
 918         blk_mq_start_request(bd->rq);
 919
 920         if (unlikely(ubq_daemon_is_dying(ubq))) {
 921                 __ublk_abort_rq(ubq, rq);
 922                 return BLK_STS_OK;
 923         }
 924
 925         ublk_queue_cmd(ubq, rq);
 926
 927         return BLK_STS_OK;
 928 }
 929
 930 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
 931                 unsigned int hctx_idx)
 932 {
 933         struct ublk_device *ub = driver_data;
 934         struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
 935
 936         hctx->driver_data = ubq;
 937         return 0;
 938 }
 939
 940 static const struct blk_mq_ops ublk_mq_ops = {
 941         .queue_rq       = ublk_queue_rq,
 942         .init_hctx      = ublk_init_hctx,
 943         .timeout        = ublk_timeout,
 944 };
 945
 946 static int ublk_ch_open(struct inode *inode, struct file *filp)
 947 {
 948         struct ublk_device *ub = container_of(inode->i_cdev,
 949                         struct ublk_device, cdev);
 950
 951         if (test_and_set_bit(UB_STATE_OPEN, &ub->state))
 952                 return -EBUSY;
 953         filp->private_data = ub;
 954         return 0;
 955 }
 956
 957 static int ublk_ch_release(struct inode *inode, struct file *filp)
 958 {
 959         struct ublk_device *ub = filp->private_data;
 960
 961         clear_bit(UB_STATE_OPEN, &ub->state);
 962         return 0;
 963 }
 964
 965 /* map pre-allocated per-queue cmd buffer to ublksrv daemon */
 966 static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
 967 {
 968         struct ublk_device *ub = filp->private_data;
 969         size_t sz = vma->vm_end - vma->vm_start;
 970         unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
 971         unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
 972         int q_id, ret = 0;
 973
 974         spin_lock(&ub->mm_lock);
 975         if (!ub->mm)
 976                 ub->mm = current->mm;
 977         if (current->mm != ub->mm)
 978                 ret = -EINVAL;
 979         spin_unlock(&ub->mm_lock);
 980
 981         if (ret)
 982                 return ret;
 983
 984         if (vma->vm_flags & VM_WRITE)
 985                 return -EPERM;
 986
 987         end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz;
 988         if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end)
 989                 return -EINVAL;
 990
 991         q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz;
 992         pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n",
 993                         __func__, q_id, current->pid, vma->vm_start,
 994                         phys_off, (unsigned long)sz);
 995
 996         if (sz != ublk_queue_cmd_buf_size(ub, q_id))
 997                 return -EINVAL;
 998
 999         pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT;
1000         return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
1001 }
1002
1003 static void ublk_commit_completion(struct ublk_device *ub,
1004                 const struct ublksrv_io_cmd *ub_cmd)
1005 {
1006         u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
1007         struct ublk_queue *ubq = ublk_get_queue(ub, qid);
1008         struct ublk_io *io = &ubq->ios[tag];
1009         struct request *req;
1010
1011         /* now this cmd slot is owned by nbd driver */
1012         io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
1013         io->res = ub_cmd->result;
1014
1015         /* find the io request and complete */
1016         req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
1017
1018         if (req && likely(!blk_should_fake_timeout(req->q)))
1019                 ublk_complete_rq(req);
1020 }
1021
1022 /*
1023  * When ->ubq_daemon is exiting, either new request is ended immediately,
1024  * or any queued io command is drained, so it is safe to abort queue
1025  * lockless
1026  */
1027 static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
1028 {
1029         int i;
1030
1031         if (!ublk_get_device(ub))
1032                 return;
1033
1034         for (i = 0; i < ubq->q_depth; i++) {
1035                 struct ublk_io *io = &ubq->ios[i];
1036
1037                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
1038                         struct request *rq;
1039
1040                         /*
1041                          * Either we fail the request or ublk_rq_task_work_fn
1042                          * will do it
1043                          */
1044                         rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
1045                         if (rq)
1046                                 __ublk_fail_req(ubq, io, rq);
1047                 }
1048         }
1049         ublk_put_device(ub);
1050 }
1051
1052 static void ublk_daemon_monitor_work(struct work_struct *work)
1053 {
1054         struct ublk_device *ub =
1055                 container_of(work, struct ublk_device, monitor_work.work);
1056         int i;
1057
1058         for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {
1059                 struct ublk_queue *ubq = ublk_get_queue(ub, i);
1060
1061                 if (ubq_daemon_is_dying(ubq)) {
1062                         if (ublk_queue_can_use_recovery(ubq))
1063                                 schedule_work(&ub->quiesce_work);
1064                         else
1065                                 schedule_work(&ub->stop_work);
1066
1067                         /* abort queue is for making forward progress */
1068                         ublk_abort_queue(ub, ubq);
1069                 }
1070         }
1071
1072         /*
1073          * We can't schedule monitor work after ub's state is not UBLK_S_DEV_LIVE.
1074          * after ublk_remove() or __ublk_quiesce_dev() is started.
1075          *
1076          * No need ub->mutex, monitor work are canceled after state is marked
1077          * as not LIVE, so new state is observed reliably.
1078          */
1079         if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1080                 schedule_delayed_work(&ub->monitor_work,
1081                                 UBLK_DAEMON_MONITOR_PERIOD);
1082 }
1083
1084 static inline bool ublk_queue_ready(struct ublk_queue *ubq)
1085 {
1086         return ubq->nr_io_ready == ubq->q_depth;
1087 }
1088
1089 static void ublk_cancel_queue(struct ublk_queue *ubq)
1090 {
1091         int i;
1092
1093         if (!ublk_queue_ready(ubq))
1094                 return;
1095
1096         for (i = 0; i < ubq->q_depth; i++) {
1097                 struct ublk_io *io = &ubq->ios[i];
1098
1099                 if (io->flags & UBLK_IO_FLAG_ACTIVE)
1100                         io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0,
1101                                                 IO_URING_F_UNLOCKED);
1102         }
1103
1104         /* all io commands are canceled */
1105         ubq->nr_io_ready = 0;
1106 }
1107
1108 /* Cancel all pending commands, must be called after del_gendisk() returns */
1109 static void ublk_cancel_dev(struct ublk_device *ub)
1110 {
1111         int i;
1112
1113         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1114                 ublk_cancel_queue(ublk_get_queue(ub, i));
1115 }
1116
1117 static bool ublk_check_inflight_rq(struct request *rq, void *data)
1118 {
1119         bool *idle = data;
1120
1121         if (blk_mq_request_started(rq)) {
1122                 *idle = false;
1123                 return false;
1124         }
1125         return true;
1126 }
1127
1128 static void ublk_wait_tagset_rqs_idle(struct ublk_device *ub)
1129 {
1130         bool idle;
1131
1132         WARN_ON_ONCE(!blk_queue_quiesced(ub->ub_disk->queue));
1133         while (true) {
1134                 idle = true;
1135                 blk_mq_tagset_busy_iter(&ub->tag_set,
1136                                 ublk_check_inflight_rq, &idle);
1137                 if (idle)
1138                         break;
1139                 msleep(UBLK_REQUEUE_DELAY_MS);
1140         }
1141 }
1142
1143 static void __ublk_quiesce_dev(struct ublk_device *ub)
1144 {
1145         pr_devel("%s: quiesce ub: dev_id %d state %s\n",
1146                         __func__, ub->dev_info.dev_id,
1147                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1148                         "LIVE" : "QUIESCED");
1149         blk_mq_quiesce_queue(ub->ub_disk->queue);
1150         ublk_wait_tagset_rqs_idle(ub);
1151         ub->dev_info.state = UBLK_S_DEV_QUIESCED;
1152         ublk_cancel_dev(ub);
1153         /* we are going to release task_struct of ubq_daemon and resets
1154          * ->ubq_daemon to NULL. So in monitor_work, check on ubq_daemon causes UAF.
1155          * Besides, monitor_work is not necessary in QUIESCED state since we have
1156          * already scheduled quiesce_work and quiesced all ubqs.
1157          *
1158          * Do not let monitor_work schedule itself if state it QUIESCED. And we cancel
1159          * it here and re-schedule it in END_USER_RECOVERY to avoid UAF.
1160          */
1161         cancel_delayed_work_sync(&ub->monitor_work);
1162 }
1163
1164 static void ublk_quiesce_work_fn(struct work_struct *work)
1165 {
1166         struct ublk_device *ub =
1167                 container_of(work, struct ublk_device, quiesce_work);
1168
1169         mutex_lock(&ub->mutex);
1170         if (ub->dev_info.state != UBLK_S_DEV_LIVE)
1171                 goto unlock;
1172         __ublk_quiesce_dev(ub);
1173  unlock:
1174         mutex_unlock(&ub->mutex);
1175 }
1176
1177 static void ublk_unquiesce_dev(struct ublk_device *ub)
1178 {
1179         int i;
1180
1181         pr_devel("%s: unquiesce ub: dev_id %d state %s\n",
1182                         __func__, ub->dev_info.dev_id,
1183                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1184                         "LIVE" : "QUIESCED");
1185         /* quiesce_work has run. We let requeued rqs be aborted
1186          * before running fallback_wq. "force_abort" must be seen
1187          * after request queue is unqiuesced. Then del_gendisk()
1188          * can move on.
1189          */
1190         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1191                 ublk_get_queue(ub, i)->force_abort = true;
1192
1193         blk_mq_unquiesce_queue(ub->ub_disk->queue);
1194         /* We may have requeued some rqs in ublk_quiesce_queue() */
1195         blk_mq_kick_requeue_list(ub->ub_disk->queue);
1196 }
1197
1198 static void ublk_stop_dev(struct ublk_device *ub)
1199 {
1200         mutex_lock(&ub->mutex);
1201         if (ub->dev_info.state == UBLK_S_DEV_DEAD)
1202                 goto unlock;
1203         if (ublk_can_use_recovery(ub)) {
1204                 if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1205                         __ublk_quiesce_dev(ub);
1206                 ublk_unquiesce_dev(ub);
1207         }
1208         del_gendisk(ub->ub_disk);
1209         ub->dev_info.state = UBLK_S_DEV_DEAD;
1210         ub->dev_info.ublksrv_pid = -1;
1211         put_disk(ub->ub_disk);
1212         ub->ub_disk = NULL;
1213  unlock:
1214         ublk_cancel_dev(ub);
1215         mutex_unlock(&ub->mutex);
1216         cancel_delayed_work_sync(&ub->monitor_work);
1217 }
1218
1219 /* device can only be started after all IOs are ready */
1220 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
1221 {
1222         mutex_lock(&ub->mutex);
1223         ubq->nr_io_ready++;
1224         if (ublk_queue_ready(ubq)) {
1225                 ubq->ubq_daemon = current;
1226                 get_task_struct(ubq->ubq_daemon);
1227                 ub->nr_queues_ready++;
1228
1229                 if (capable(CAP_SYS_ADMIN))
1230                         ub->nr_privileged_daemon++;
1231         }
1232         if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
1233                 complete_all(&ub->completion);
1234         mutex_unlock(&ub->mutex);
1235 }
1236
1237 static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
1238                 int tag)
1239 {
1240         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1241         struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
1242
1243         ublk_queue_cmd(ubq, req);
1244 }
1245
1246 static inline int ublk_check_cmd_op(u32 cmd_op)
1247 {
1248         u32 ioc_type = _IOC_TYPE(cmd_op);
1249
1250         if (!IS_ENABLED(CONFIG_BLKDEV_UBLK_LEGACY_OPCODES) && ioc_type != 'u')
1251                 return -EOPNOTSUPP;
1252
1253         if (ioc_type != 'u' && ioc_type != 0)
1254                 return -EOPNOTSUPP;
1255
1256         return 0;
1257 }
1258
1259 static inline void ublk_fill_io_cmd(struct ublk_io *io,
1260                 struct io_uring_cmd *cmd, unsigned long buf_addr)
1261 {
1262         io->cmd = cmd;
1263         io->flags |= UBLK_IO_FLAG_ACTIVE;
1264         io->addr = buf_addr;
1265 }
1266
1267 static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
1268                                unsigned int issue_flags,
1269                                const struct ublksrv_io_cmd *ub_cmd)
1270 {
1271         struct ublk_device *ub = cmd->file->private_data;
1272         struct ublk_queue *ubq;
1273         struct ublk_io *io;
1274         u32 cmd_op = cmd->cmd_op;
1275         unsigned tag = ub_cmd->tag;
1276         int ret = -EINVAL;
1277         struct request *req;
1278
1279         pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
1280                         __func__, cmd->cmd_op, ub_cmd->q_id, tag,
1281                         ub_cmd->result);
1282
1283         if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues)
1284                 goto out;
1285
1286         ubq = ublk_get_queue(ub, ub_cmd->q_id);
1287         if (!ubq || ub_cmd->q_id != ubq->q_id)
1288                 goto out;
1289
1290         if (ubq->ubq_daemon && ubq->ubq_daemon != current)
1291                 goto out;
1292
1293         if (tag >= ubq->q_depth)
1294                 goto out;
1295
1296         io = &ubq->ios[tag];
1297
1298         /* there is pending io cmd, something must be wrong */
1299         if (io->flags & UBLK_IO_FLAG_ACTIVE) {
1300                 ret = -EBUSY;
1301                 goto out;
1302         }
1303
1304         /*
1305          * ensure that the user issues UBLK_IO_NEED_GET_DATA
1306          * iff the driver have set the UBLK_IO_FLAG_NEED_GET_DATA.
1307          */
1308         if ((!!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA))
1309                         ^ (_IOC_NR(cmd_op) == UBLK_IO_NEED_GET_DATA))
1310                 goto out;
1311
1312         ret = ublk_check_cmd_op(cmd_op);
1313         if (ret)
1314                 goto out;
1315
1316         ret = -EINVAL;
1317         switch (_IOC_NR(cmd_op)) {
1318         case UBLK_IO_FETCH_REQ:
1319                 /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
1320                 if (ublk_queue_ready(ubq)) {
1321                         ret = -EBUSY;
1322                         goto out;
1323                 }
1324                 /*
1325                  * The io is being handled by server, so COMMIT_RQ is expected
1326                  * instead of FETCH_REQ
1327                  */
1328                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
1329                         goto out;
1330                 /* FETCH_RQ has to provide IO buffer if NEED GET DATA is not enabled */
1331                 if (!ub_cmd->addr && !ublk_need_get_data(ubq))
1332                         goto out;
1333
1334                 ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
1335                 ublk_mark_io_ready(ub, ubq);
1336                 break;
1337         case UBLK_IO_COMMIT_AND_FETCH_REQ:
1338                 req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag);
1339                 /*
1340                  * COMMIT_AND_FETCH_REQ has to provide IO buffer if NEED GET DATA is
1341                  * not enabled or it is Read IO.
1342                  */
1343                 if (!ub_cmd->addr && (!ublk_need_get_data(ubq) || req_op(req) == REQ_OP_READ))
1344                         goto out;
1345                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1346                         goto out;
1347                 ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
1348                 ublk_commit_completion(ub, ub_cmd);
1349                 break;
1350         case UBLK_IO_NEED_GET_DATA:
1351                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1352                         goto out;
1353                 ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
1354                 ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag);
1355                 break;
1356         default:
1357                 goto out;
1358         }
1359         return -EIOCBQUEUED;
1360
1361  out:
1362         io_uring_cmd_done(cmd, ret, 0, issue_flags);
1363         pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
1364                         __func__, cmd_op, tag, ret, io->flags);
1365         return -EIOCBQUEUED;
1366 }
1367
1368 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
1369 {
1370         /*
1371          * Not necessary for async retry, but let's keep it simple and always
1372          * copy the values to avoid any potential reuse.
1373          */
1374         const struct ublksrv_io_cmd *ub_src = io_uring_sqe_cmd(cmd->sqe);
1375         const struct ublksrv_io_cmd ub_cmd = {
1376                 .q_id = READ_ONCE(ub_src->q_id),
1377                 .tag = READ_ONCE(ub_src->tag),
1378                 .result = READ_ONCE(ub_src->result),
1379                 .addr = READ_ONCE(ub_src->addr)
1380         };
1381
1382         return __ublk_ch_uring_cmd(cmd, issue_flags, &ub_cmd);
1383 }
1384
1385 static const struct file_operations ublk_ch_fops = {
1386         .owner = THIS_MODULE,
1387         .open = ublk_ch_open,
1388         .release = ublk_ch_release,
1389         .llseek = no_llseek,
1390         .uring_cmd = ublk_ch_uring_cmd,
1391         .mmap = ublk_ch_mmap,
1392 };
1393
1394 static void ublk_deinit_queue(struct ublk_device *ub, int q_id)
1395 {
1396         int size = ublk_queue_cmd_buf_size(ub, q_id);
1397         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1398
1399         if (ubq->ubq_daemon)
1400                 put_task_struct(ubq->ubq_daemon);
1401         if (ubq->io_cmd_buf)
1402                 free_pages((unsigned long)ubq->io_cmd_buf, get_order(size));
1403 }
1404
1405 static int ublk_init_queue(struct ublk_device *ub, int q_id)
1406 {
1407         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1408         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO;
1409         void *ptr;
1410         int size;
1411
1412         ubq->flags = ub->dev_info.flags;
1413         ubq->q_id = q_id;
1414         ubq->q_depth = ub->dev_info.queue_depth;
1415         size = ublk_queue_cmd_buf_size(ub, q_id);
1416
1417         ptr = (void *) __get_free_pages(gfp_flags, get_order(size));
1418         if (!ptr)
1419                 return -ENOMEM;
1420
1421         ubq->io_cmd_buf = ptr;
1422         ubq->dev = ub;
1423         return 0;
1424 }
1425
1426 static void ublk_deinit_queues(struct ublk_device *ub)
1427 {
1428         int nr_queues = ub->dev_info.nr_hw_queues;
1429         int i;
1430
1431         if (!ub->__queues)
1432                 return;
1433
1434         for (i = 0; i < nr_queues; i++)
1435                 ublk_deinit_queue(ub, i);
1436         kfree(ub->__queues);
1437 }
1438
1439 static int ublk_init_queues(struct ublk_device *ub)
1440 {
1441         int nr_queues = ub->dev_info.nr_hw_queues;
1442         int depth = ub->dev_info.queue_depth;
1443         int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io);
1444         int i, ret = -ENOMEM;
1445
1446         ub->queue_size = ubq_size;
1447         ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
1448         if (!ub->__queues)
1449                 return ret;
1450
1451         for (i = 0; i < nr_queues; i++) {
1452                 if (ublk_init_queue(ub, i))
1453                         goto fail;
1454         }
1455
1456         init_completion(&ub->completion);
1457         return 0;
1458
1459  fail:
1460         ublk_deinit_queues(ub);
1461         return ret;
1462 }
1463
1464 static int ublk_alloc_dev_number(struct ublk_device *ub, int idx)
1465 {
1466         int i = idx;
1467         int err;
1468
1469         spin_lock(&ublk_idr_lock);
1470         /* allocate id, if @id >= 0, we're requesting that specific id */
1471         if (i >= 0) {
1472                 err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT);
1473                 if (err == -ENOSPC)
1474                         err = -EEXIST;
1475         } else {
1476                 err = idr_alloc(&ublk_index_idr, ub, 0, 0, GFP_NOWAIT);
1477         }
1478         spin_unlock(&ublk_idr_lock);
1479
1480         if (err >= 0)
1481                 ub->ub_number = err;
1482
1483         return err;
1484 }
1485
1486 static void ublk_free_dev_number(struct ublk_device *ub)
1487 {
1488         spin_lock(&ublk_idr_lock);
1489         idr_remove(&ublk_index_idr, ub->ub_number);
1490         wake_up_all(&ublk_idr_wq);
1491         spin_unlock(&ublk_idr_lock);
1492 }
1493
1494 static void ublk_cdev_rel(struct device *dev)
1495 {
1496         struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
1497
1498         blk_mq_free_tag_set(&ub->tag_set);
1499         ublk_deinit_queues(ub);
1500         ublk_free_dev_number(ub);
1501         mutex_destroy(&ub->mutex);
1502         kfree(ub);
1503 }
1504
1505 static int ublk_add_chdev(struct ublk_device *ub)
1506 {
1507         struct device *dev = &ub->cdev_dev;
1508         int minor = ub->ub_number;
1509         int ret;
1510
1511         dev->parent = ublk_misc.this_device;
1512         dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor);
1513         dev->class = ublk_chr_class;
1514         dev->release = ublk_cdev_rel;
1515         device_initialize(dev);
1516
1517         ret = dev_set_name(dev, "ublkc%d", minor);
1518         if (ret)
1519                 goto fail;
1520
1521         cdev_init(&ub->cdev, &ublk_ch_fops);
1522         ret = cdev_device_add(&ub->cdev, dev);
1523         if (ret)
1524                 goto fail;
1525
1526         ublks_added++;
1527         return 0;
1528  fail:
1529         put_device(dev);
1530         return ret;
1531 }
1532
1533 static void ublk_stop_work_fn(struct work_struct *work)
1534 {
1535         struct ublk_device *ub =
1536                 container_of(work, struct ublk_device, stop_work);
1537
1538         ublk_stop_dev(ub);
1539 }
1540
1541 /* align max io buffer size with PAGE_SIZE */
1542 static void ublk_align_max_io_size(struct ublk_device *ub)
1543 {
1544         unsigned int max_io_bytes = ub->dev_info.max_io_buf_bytes;
1545
1546         ub->dev_info.max_io_buf_bytes =
1547                 round_down(max_io_bytes, PAGE_SIZE);
1548 }
1549
1550 static int ublk_add_tag_set(struct ublk_device *ub)
1551 {
1552         ub->tag_set.ops = &ublk_mq_ops;
1553         ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues;
1554         ub->tag_set.queue_depth = ub->dev_info.queue_depth;
1555         ub->tag_set.numa_node = NUMA_NO_NODE;
1556         ub->tag_set.cmd_size = sizeof(struct ublk_rq_data);
1557         ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1558         ub->tag_set.driver_data = ub;
1559         return blk_mq_alloc_tag_set(&ub->tag_set);
1560 }
1561
1562 static void ublk_remove(struct ublk_device *ub)
1563 {
1564         ublk_stop_dev(ub);
1565         cancel_work_sync(&ub->stop_work);
1566         cancel_work_sync(&ub->quiesce_work);
1567         cdev_device_del(&ub->cdev, &ub->cdev_dev);
1568         put_device(&ub->cdev_dev);
1569         ublks_added--;
1570 }
1571
1572 static struct ublk_device *ublk_get_device_from_id(int idx)
1573 {
1574         struct ublk_device *ub = NULL;
1575
1576         if (idx < 0)
1577                 return NULL;
1578
1579         spin_lock(&ublk_idr_lock);
1580         ub = idr_find(&ublk_index_idr, idx);
1581         if (ub)
1582                 ub = ublk_get_device(ub);
1583         spin_unlock(&ublk_idr_lock);
1584
1585         return ub;
1586 }
1587
1588 static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
1589 {
1590         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
1591         int ublksrv_pid = (int)header->data[0];
1592         struct gendisk *disk;
1593         int ret = -EINVAL;
1594
1595         if (ublksrv_pid <= 0)
1596                 return -EINVAL;
1597
1598         wait_for_completion_interruptible(&ub->completion);
1599
1600         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
1601
1602         mutex_lock(&ub->mutex);
1603         if (ub->dev_info.state == UBLK_S_DEV_LIVE ||
1604             test_bit(UB_STATE_USED, &ub->state)) {
1605                 ret = -EEXIST;
1606                 goto out_unlock;
1607         }
1608
1609         disk = blk_mq_alloc_disk(&ub->tag_set, NULL);
1610         if (IS_ERR(disk)) {
1611                 ret = PTR_ERR(disk);
1612                 goto out_unlock;
1613         }
1614         sprintf(disk->disk_name, "ublkb%d", ub->ub_number);
1615         disk->fops = &ub_fops;
1616         disk->private_data = ub;
1617
1618         ub->dev_info.ublksrv_pid = ublksrv_pid;
1619         ub->ub_disk = disk;
1620
1621         ret = ublk_apply_params(ub);
1622         if (ret)
1623                 goto out_put_disk;
1624
1625         /* don't probe partitions if any one ubq daemon is un-trusted */
1626         if (ub->nr_privileged_daemon != ub->nr_queues_ready)
1627                 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
1628
1629         get_device(&ub->cdev_dev);
1630         ub->dev_info.state = UBLK_S_DEV_LIVE;
1631         ret = add_disk(disk);
1632         if (ret) {
1633                 /*
1634                  * Has to drop the reference since ->free_disk won't be
1635                  * called in case of add_disk failure.
1636                  */
1637                 ub->dev_info.state = UBLK_S_DEV_DEAD;
1638                 ublk_put_device(ub);
1639                 goto out_put_disk;
1640         }
1641         set_bit(UB_STATE_USED, &ub->state);
1642 out_put_disk:
1643         if (ret)
1644                 put_disk(disk);
1645 out_unlock:
1646         mutex_unlock(&ub->mutex);
1647         return ret;
1648 }
1649
1650 static int ublk_ctrl_get_queue_affinity(struct ublk_device *ub,
1651                 struct io_uring_cmd *cmd)
1652 {
1653         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
1654         void __user *argp = (void __user *)(unsigned long)header->addr;
1655         cpumask_var_t cpumask;
1656         unsigned long queue;
1657         unsigned int retlen;
1658         unsigned int i;
1659         int ret;
1660
1661         if (header->len * BITS_PER_BYTE < nr_cpu_ids)
1662                 return -EINVAL;
1663         if (header->len & (sizeof(unsigned long)-1))
1664                 return -EINVAL;
1665         if (!header->addr)
1666                 return -EINVAL;
1667
1668         queue = header->data[0];
1669         if (queue >= ub->dev_info.nr_hw_queues)
1670                 return -EINVAL;
1671
1672         if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
1673                 return -ENOMEM;
1674
1675         for_each_possible_cpu(i) {
1676                 if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] == queue)
1677                         cpumask_set_cpu(i, cpumask);
1678         }
1679
1680         ret = -EFAULT;
1681         retlen = min_t(unsigned short, header->len, cpumask_size());
1682         if (copy_to_user(argp, cpumask, retlen))
1683                 goto out_free_cpumask;
1684         if (retlen != header->len &&
1685             clear_user(argp + retlen, header->len - retlen))
1686                 goto out_free_cpumask;
1687
1688         ret = 0;
1689 out_free_cpumask:
1690         free_cpumask_var(cpumask);
1691         return ret;
1692 }
1693
1694 static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info)
1695 {
1696         pr_devel("%s: dev id %d flags %llx\n", __func__,
1697                         info->dev_id, info->flags);
1698         pr_devel("\t nr_hw_queues %d queue_depth %d\n",
1699                         info->nr_hw_queues, info->queue_depth);
1700 }
1701
1702 static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
1703 {
1704         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
1705         void __user *argp = (void __user *)(unsigned long)header->addr;
1706         struct ublksrv_ctrl_dev_info info;
1707         struct ublk_device *ub;
1708         int ret = -EINVAL;
1709
1710         if (header->len < sizeof(info) || !header->addr)
1711                 return -EINVAL;
1712         if (header->queue_id != (u16)-1) {
1713                 pr_warn("%s: queue_id is wrong %x\n",
1714                         __func__, header->queue_id);
1715                 return -EINVAL;
1716         }
1717
1718         if (copy_from_user(&info, argp, sizeof(info)))
1719                 return -EFAULT;
1720
1721         if (capable(CAP_SYS_ADMIN))
1722                 info.flags &= ~UBLK_F_UNPRIVILEGED_DEV;
1723         else if (!(info.flags & UBLK_F_UNPRIVILEGED_DEV))
1724                 return -EPERM;
1725
1726         /*
1727          * unprivileged device can't be trusted, but RECOVERY and
1728          * RECOVERY_REISSUE still may hang error handling, so can't
1729          * support recovery features for unprivileged ublk now
1730          *
1731          * TODO: provide forward progress for RECOVERY handler, so that
1732          * unprivileged device can benefit from it
1733          */
1734         if (info.flags & UBLK_F_UNPRIVILEGED_DEV)
1735                 info.flags &= ~(UBLK_F_USER_RECOVERY_REISSUE |
1736                                 UBLK_F_USER_RECOVERY);
1737
1738         /* the created device is always owned by current user */
1739         ublk_store_owner_uid_gid(&info.owner_uid, &info.owner_gid);
1740
1741         if (header->dev_id != info.dev_id) {
1742                 pr_warn("%s: dev id not match %u %u\n",
1743                         __func__, header->dev_id, info.dev_id);
1744                 return -EINVAL;
1745         }
1746
1747         ublk_dump_dev_info(&info);
1748
1749         ret = mutex_lock_killable(&ublk_ctl_mutex);
1750         if (ret)
1751                 return ret;
1752
1753         ret = -EACCES;
1754         if (ublks_added >= ublks_max)
1755                 goto out_unlock;
1756
1757         ret = -ENOMEM;
1758         ub = kzalloc(sizeof(*ub), GFP_KERNEL);
1759         if (!ub)
1760                 goto out_unlock;
1761         mutex_init(&ub->mutex);
1762         spin_lock_init(&ub->mm_lock);
1763         INIT_WORK(&ub->quiesce_work, ublk_quiesce_work_fn);
1764         INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
1765         INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work);
1766
1767         ret = ublk_alloc_dev_number(ub, header->dev_id);
1768         if (ret < 0)
1769                 goto out_free_ub;
1770
1771         memcpy(&ub->dev_info, &info, sizeof(info));
1772
1773         /* update device id */
1774         ub->dev_info.dev_id = ub->ub_number;
1775
1776         /*
1777          * 64bit flags will be copied back to userspace as feature
1778          * negotiation result, so have to clear flags which driver
1779          * doesn't support yet, then userspace can get correct flags
1780          * (features) to handle.
1781          */
1782         ub->dev_info.flags &= UBLK_F_ALL;
1783
1784         ub->dev_info.flags |= UBLK_F_CMD_IOCTL_ENCODE |
1785                 UBLK_F_URING_CMD_COMP_IN_TASK;
1786
1787         /* We are not ready to support zero copy */
1788         ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
1789
1790         ub->dev_info.nr_hw_queues = min_t(unsigned int,
1791                         ub->dev_info.nr_hw_queues, nr_cpu_ids);
1792         ublk_align_max_io_size(ub);
1793
1794         ret = ublk_init_queues(ub);
1795         if (ret)
1796                 goto out_free_dev_number;
1797
1798         ret = ublk_add_tag_set(ub);
1799         if (ret)
1800                 goto out_deinit_queues;
1801
1802         ret = -EFAULT;
1803         if (copy_to_user(argp, &ub->dev_info, sizeof(info)))
1804                 goto out_free_tag_set;
1805
1806         /*
1807          * Add the char dev so that ublksrv daemon can be setup.
1808          * ublk_add_chdev() will cleanup everything if it fails.
1809          */
1810         ret = ublk_add_chdev(ub);
1811         goto out_unlock;
1812
1813 out_free_tag_set:
1814         blk_mq_free_tag_set(&ub->tag_set);
1815 out_deinit_queues:
1816         ublk_deinit_queues(ub);
1817 out_free_dev_number:
1818         ublk_free_dev_number(ub);
1819 out_free_ub:
1820         mutex_destroy(&ub->mutex);
1821         kfree(ub);
1822 out_unlock:
1823         mutex_unlock(&ublk_ctl_mutex);
1824         return ret;
1825 }
1826
1827 static inline bool ublk_idr_freed(int id)
1828 {
1829         void *ptr;
1830
1831         spin_lock(&ublk_idr_lock);
1832         ptr = idr_find(&ublk_index_idr, id);
1833         spin_unlock(&ublk_idr_lock);
1834
1835         return ptr == NULL;
1836 }
1837
1838 static int ublk_ctrl_del_dev(struct ublk_device **p_ub)
1839 {
1840         struct ublk_device *ub = *p_ub;
1841         int idx = ub->ub_number;
1842         int ret;
1843
1844         ret = mutex_lock_killable(&ublk_ctl_mutex);
1845         if (ret)
1846                 return ret;
1847
1848         if (!test_bit(UB_STATE_DELETED, &ub->state)) {
1849                 ublk_remove(ub);
1850                 set_bit(UB_STATE_DELETED, &ub->state);
1851         }
1852
1853         /* Mark the reference as consumed */
1854         *p_ub = NULL;
1855         ublk_put_device(ub);
1856         mutex_unlock(&ublk_ctl_mutex);
1857
1858         /*
1859          * Wait until the idr is removed, then it can be reused after
1860          * DEL_DEV command is returned.
1861          *
1862          * If we returns because of user interrupt, future delete command
1863          * may come:
1864          *
1865          * - the device number isn't freed, this device won't or needn't
1866          *   be deleted again, since UB_STATE_DELETED is set, and device
1867          *   will be released after the last reference is dropped
1868          *
1869          * - the device number is freed already, we will not find this
1870          *   device via ublk_get_device_from_id()
1871          */
1872         wait_event_interruptible(ublk_idr_wq, ublk_idr_freed(idx));
1873
1874         return 0;
1875 }
1876
1877 static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
1878 {
1879         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
1880
1881         pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n",
1882                         __func__, cmd->cmd_op, header->dev_id, header->queue_id,
1883                         header->data[0], header->addr, header->len);
1884 }
1885
1886 static int ublk_ctrl_stop_dev(struct ublk_device *ub)
1887 {
1888         ublk_stop_dev(ub);
1889         cancel_work_sync(&ub->stop_work);
1890         cancel_work_sync(&ub->quiesce_work);
1891
1892         return 0;
1893 }
1894
1895 static int ublk_ctrl_get_dev_info(struct ublk_device *ub,
1896                 struct io_uring_cmd *cmd)
1897 {
1898         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
1899         void __user *argp = (void __user *)(unsigned long)header->addr;
1900
1901         if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr)
1902                 return -EINVAL;
1903
1904         if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info)))
1905                 return -EFAULT;
1906
1907         return 0;
1908 }
1909
1910 /* TYPE_DEVT is readonly, so fill it up before returning to userspace */
1911 static void ublk_ctrl_fill_params_devt(struct ublk_device *ub)
1912 {
1913         ub->params.devt.char_major = MAJOR(ub->cdev_dev.devt);
1914         ub->params.devt.char_minor = MINOR(ub->cdev_dev.devt);
1915
1916         if (ub->ub_disk) {
1917                 ub->params.devt.disk_major = MAJOR(disk_devt(ub->ub_disk));
1918                 ub->params.devt.disk_minor = MINOR(disk_devt(ub->ub_disk));
1919         } else {
1920                 ub->params.devt.disk_major = 0;
1921                 ub->params.devt.disk_minor = 0;
1922         }
1923         ub->params.types |= UBLK_PARAM_TYPE_DEVT;
1924 }
1925
1926 static int ublk_ctrl_get_params(struct ublk_device *ub,
1927                 struct io_uring_cmd *cmd)
1928 {
1929         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
1930         void __user *argp = (void __user *)(unsigned long)header->addr;
1931         struct ublk_params_header ph;
1932         int ret;
1933
1934         if (header->len <= sizeof(ph) || !header->addr)
1935                 return -EINVAL;
1936
1937         if (copy_from_user(&ph, argp, sizeof(ph)))
1938                 return -EFAULT;
1939
1940         if (ph.len > header->len || !ph.len)
1941                 return -EINVAL;
1942
1943         if (ph.len > sizeof(struct ublk_params))
1944                 ph.len = sizeof(struct ublk_params);
1945
1946         mutex_lock(&ub->mutex);
1947         ublk_ctrl_fill_params_devt(ub);
1948         if (copy_to_user(argp, &ub->params, ph.len))
1949                 ret = -EFAULT;
1950         else
1951                 ret = 0;
1952         mutex_unlock(&ub->mutex);
1953
1954         return ret;
1955 }
1956
1957 static int ublk_ctrl_set_params(struct ublk_device *ub,
1958                 struct io_uring_cmd *cmd)
1959 {
1960         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
1961         void __user *argp = (void __user *)(unsigned long)header->addr;
1962         struct ublk_params_header ph;
1963         int ret = -EFAULT;
1964
1965         if (header->len <= sizeof(ph) || !header->addr)
1966                 return -EINVAL;
1967
1968         if (copy_from_user(&ph, argp, sizeof(ph)))
1969                 return -EFAULT;
1970
1971         if (ph.len > header->len || !ph.len || !ph.types)
1972                 return -EINVAL;
1973
1974         if (ph.len > sizeof(struct ublk_params))
1975                 ph.len = sizeof(struct ublk_params);
1976
1977         /* parameters can only be changed when device isn't live */
1978         mutex_lock(&ub->mutex);
1979         if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
1980                 ret = -EACCES;
1981         } else if (copy_from_user(&ub->params, argp, ph.len)) {
1982                 ret = -EFAULT;
1983         } else {
1984                 /* clear all we don't support yet */
1985                 ub->params.types &= UBLK_PARAM_TYPE_ALL;
1986                 ret = ublk_validate_params(ub);
1987                 if (ret)
1988                         ub->params.types = 0;
1989         }
1990         mutex_unlock(&ub->mutex);
1991
1992         return ret;
1993 }
1994
1995 static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
1996 {
1997         int i;
1998
1999         WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
2000         /* All old ioucmds have to be completed */
2001         WARN_ON_ONCE(ubq->nr_io_ready);
2002         /* old daemon is PF_EXITING, put it now */
2003         put_task_struct(ubq->ubq_daemon);
2004         /* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */
2005         ubq->ubq_daemon = NULL;
2006         ubq->timeout = false;
2007
2008         for (i = 0; i < ubq->q_depth; i++) {
2009                 struct ublk_io *io = &ubq->ios[i];
2010
2011                 /* forget everything now and be ready for new FETCH_REQ */
2012                 io->flags = 0;
2013                 io->cmd = NULL;
2014                 io->addr = 0;
2015         }
2016 }
2017
2018 static int ublk_ctrl_start_recovery(struct ublk_device *ub,
2019                 struct io_uring_cmd *cmd)
2020 {
2021         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2022         int ret = -EINVAL;
2023         int i;
2024
2025         mutex_lock(&ub->mutex);
2026         if (!ublk_can_use_recovery(ub))
2027                 goto out_unlock;
2028         /*
2029          * START_RECOVERY is only allowd after:
2030          *
2031          * (1) UB_STATE_OPEN is not set, which means the dying process is exited
2032          *     and related io_uring ctx is freed so file struct of /dev/ublkcX is
2033          *     released.
2034          *
2035          * (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work:
2036          *     (a)has quiesced request queue
2037          *     (b)has requeued every inflight rqs whose io_flags is ACTIVE
2038          *     (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE
2039          *     (d)has completed/camceled all ioucmds owned by ther dying process
2040          */
2041         if (test_bit(UB_STATE_OPEN, &ub->state) ||
2042                         ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2043                 ret = -EBUSY;
2044                 goto out_unlock;
2045         }
2046         pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id);
2047         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
2048                 ublk_queue_reinit(ub, ublk_get_queue(ub, i));
2049         /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */
2050         ub->mm = NULL;
2051         ub->nr_queues_ready = 0;
2052         ub->nr_privileged_daemon = 0;
2053         init_completion(&ub->completion);
2054         ret = 0;
2055  out_unlock:
2056         mutex_unlock(&ub->mutex);
2057         return ret;
2058 }
2059
2060 static int ublk_ctrl_end_recovery(struct ublk_device *ub,
2061                 struct io_uring_cmd *cmd)
2062 {
2063         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2064         int ublksrv_pid = (int)header->data[0];
2065         int ret = -EINVAL;
2066
2067         pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n",
2068                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2069         /* wait until new ubq_daemon sending all FETCH_REQ */
2070         wait_for_completion_interruptible(&ub->completion);
2071         pr_devel("%s: All new ubq_daemons(nr: %d) are ready, dev id %d\n",
2072                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2073
2074         mutex_lock(&ub->mutex);
2075         if (!ublk_can_use_recovery(ub))
2076                 goto out_unlock;
2077
2078         if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2079                 ret = -EBUSY;
2080                 goto out_unlock;
2081         }
2082         ub->dev_info.ublksrv_pid = ublksrv_pid;
2083         pr_devel("%s: new ublksrv_pid %d, dev id %d\n",
2084                         __func__, ublksrv_pid, header->dev_id);
2085         blk_mq_unquiesce_queue(ub->ub_disk->queue);
2086         pr_devel("%s: queue unquiesced, dev id %d.\n",
2087                         __func__, header->dev_id);
2088         blk_mq_kick_requeue_list(ub->ub_disk->queue);
2089         ub->dev_info.state = UBLK_S_DEV_LIVE;
2090         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
2091         ret = 0;
2092  out_unlock:
2093         mutex_unlock(&ub->mutex);
2094         return ret;
2095 }
2096
2097 /*
2098  * All control commands are sent via /dev/ublk-control, so we have to check
2099  * the destination device's permission
2100  */
2101 static int ublk_char_dev_permission(struct ublk_device *ub,
2102                 const char *dev_path, int mask)
2103 {
2104         int err;
2105         struct path path;
2106         struct kstat stat;
2107
2108         err = kern_path(dev_path, LOOKUP_FOLLOW, &path);
2109         if (err)
2110                 return err;
2111
2112         err = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
2113         if (err)
2114                 goto exit;
2115
2116         err = -EPERM;
2117         if (stat.rdev != ub->cdev_dev.devt || !S_ISCHR(stat.mode))
2118                 goto exit;
2119
2120         err = inode_permission(&nop_mnt_idmap,
2121                         d_backing_inode(path.dentry), mask);
2122 exit:
2123         path_put(&path);
2124         return err;
2125 }
2126
2127 static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
2128                 struct io_uring_cmd *cmd)
2129 {
2130         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)io_uring_sqe_cmd(cmd->sqe);
2131         bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV;
2132         void __user *argp = (void __user *)(unsigned long)header->addr;
2133         char *dev_path = NULL;
2134         int ret = 0;
2135         int mask;
2136
2137         if (!unprivileged) {
2138                 if (!capable(CAP_SYS_ADMIN))
2139                         return -EPERM;
2140                 /*
2141                  * The new added command of UBLK_CMD_GET_DEV_INFO2 includes
2142                  * char_dev_path in payload too, since userspace may not
2143                  * know if the specified device is created as unprivileged
2144                  * mode.
2145                  */
2146                 if (_IOC_NR(cmd->cmd_op) != UBLK_CMD_GET_DEV_INFO2)
2147                         return 0;
2148         }
2149
2150         /*
2151          * User has to provide the char device path for unprivileged ublk
2152          *
2153          * header->addr always points to the dev path buffer, and
2154          * header->dev_path_len records length of dev path buffer.
2155          */
2156         if (!header->dev_path_len || header->dev_path_len > PATH_MAX)
2157                 return -EINVAL;
2158
2159         if (header->len < header->dev_path_len)
2160                 return -EINVAL;
2161
2162         dev_path = kmalloc(header->dev_path_len + 1, GFP_KERNEL);
2163         if (!dev_path)
2164                 return -ENOMEM;
2165
2166         ret = -EFAULT;
2167         if (copy_from_user(dev_path, argp, header->dev_path_len))
2168                 goto exit;
2169         dev_path[header->dev_path_len] = 0;
2170
2171         ret = -EINVAL;
2172         switch (_IOC_NR(cmd->cmd_op)) {
2173         case UBLK_CMD_GET_DEV_INFO:
2174         case UBLK_CMD_GET_DEV_INFO2:
2175         case UBLK_CMD_GET_QUEUE_AFFINITY:
2176         case UBLK_CMD_GET_PARAMS:
2177                 mask = MAY_READ;
2178                 break;
2179         case UBLK_CMD_START_DEV:
2180         case UBLK_CMD_STOP_DEV:
2181         case UBLK_CMD_ADD_DEV:
2182         case UBLK_CMD_DEL_DEV:
2183         case UBLK_CMD_SET_PARAMS:
2184         case UBLK_CMD_START_USER_RECOVERY:
2185         case UBLK_CMD_END_USER_RECOVERY:
2186                 mask = MAY_READ | MAY_WRITE;
2187                 break;
2188         default:
2189                 goto exit;
2190         }
2191
2192         ret = ublk_char_dev_permission(ub, dev_path, mask);
2193         if (!ret) {
2194                 header->len -= header->dev_path_len;
2195                 header->addr += header->dev_path_len;
2196         }
2197         pr_devel("%s: dev id %d cmd_op %x uid %d gid %d path %s ret %d\n",
2198                         __func__, ub->ub_number, cmd->cmd_op,
2199                         ub->dev_info.owner_uid, ub->dev_info.owner_gid,
2200                         dev_path, ret);
2201 exit:
2202         kfree(dev_path);
2203         return ret;
2204 }
2205
2206 static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
2207                 unsigned int issue_flags)
2208 {
2209         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2210         struct ublk_device *ub = NULL;
2211         u32 cmd_op = cmd->cmd_op;
2212         int ret = -EINVAL;
2213
2214         if (issue_flags & IO_URING_F_NONBLOCK)
2215                 return -EAGAIN;
2216
2217         ublk_ctrl_cmd_dump(cmd);
2218
2219         if (!(issue_flags & IO_URING_F_SQE128))
2220                 goto out;
2221
2222         ret = ublk_check_cmd_op(cmd_op);
2223         if (ret)
2224                 goto out;
2225
2226         if (_IOC_NR(cmd_op) != UBLK_CMD_ADD_DEV) {
2227                 ret = -ENODEV;
2228                 ub = ublk_get_device_from_id(header->dev_id);
2229                 if (!ub)
2230                         goto out;
2231
2232                 ret = ublk_ctrl_uring_cmd_permission(ub, cmd);
2233                 if (ret)
2234                         goto put_dev;
2235         }
2236
2237         switch (_IOC_NR(cmd_op)) {
2238         case UBLK_CMD_START_DEV:
2239                 ret = ublk_ctrl_start_dev(ub, cmd);
2240                 break;
2241         case UBLK_CMD_STOP_DEV:
2242                 ret = ublk_ctrl_stop_dev(ub);
2243                 break;
2244         case UBLK_CMD_GET_DEV_INFO:
2245         case UBLK_CMD_GET_DEV_INFO2:
2246                 ret = ublk_ctrl_get_dev_info(ub, cmd);
2247                 break;
2248         case UBLK_CMD_ADD_DEV:
2249                 ret = ublk_ctrl_add_dev(cmd);
2250                 break;
2251         case UBLK_CMD_DEL_DEV:
2252                 ret = ublk_ctrl_del_dev(&ub);
2253                 break;
2254         case UBLK_CMD_GET_QUEUE_AFFINITY:
2255                 ret = ublk_ctrl_get_queue_affinity(ub, cmd);
2256                 break;
2257         case UBLK_CMD_GET_PARAMS:
2258                 ret = ublk_ctrl_get_params(ub, cmd);
2259                 break;
2260         case UBLK_CMD_SET_PARAMS:
2261                 ret = ublk_ctrl_set_params(ub, cmd);
2262                 break;
2263         case UBLK_CMD_START_USER_RECOVERY:
2264                 ret = ublk_ctrl_start_recovery(ub, cmd);
2265                 break;
2266         case UBLK_CMD_END_USER_RECOVERY:
2267                 ret = ublk_ctrl_end_recovery(ub, cmd);
2268                 break;
2269         default:
2270                 ret = -ENOTSUPP;
2271                 break;
2272         }
2273
2274  put_dev:
2275         if (ub)
2276                 ublk_put_device(ub);
2277  out:
2278         io_uring_cmd_done(cmd, ret, 0, issue_flags);
2279         pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
2280                         __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
2281         return -EIOCBQUEUED;
2282 }
2283
2284 static const struct file_operations ublk_ctl_fops = {
2285         .open           = nonseekable_open,
2286         .uring_cmd      = ublk_ctrl_uring_cmd,
2287         .owner          = THIS_MODULE,
2288         .llseek         = noop_llseek,
2289 };
2290
2291 static struct miscdevice ublk_misc = {
2292         .minor          = MISC_DYNAMIC_MINOR,
2293         .name           = "ublk-control",
2294         .fops           = &ublk_ctl_fops,
2295 };
2296
2297 static int __init ublk_init(void)
2298 {
2299         int ret;
2300
2301         init_waitqueue_head(&ublk_idr_wq);
2302
2303         ret = misc_register(&ublk_misc);
2304         if (ret)
2305                 return ret;
2306
2307         ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char");
2308         if (ret)
2309                 goto unregister_mis;
2310
2311         ublk_chr_class = class_create("ublk-char");
2312         if (IS_ERR(ublk_chr_class)) {
2313                 ret = PTR_ERR(ublk_chr_class);
2314                 goto free_chrdev_region;
2315         }
2316         return 0;
2317
2318 free_chrdev_region:
2319         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2320 unregister_mis:
2321         misc_deregister(&ublk_misc);
2322         return ret;
2323 }
2324
2325 static void __exit ublk_exit(void)
2326 {
2327         struct ublk_device *ub;
2328         int id;
2329
2330         idr_for_each_entry(&ublk_index_idr, ub, id)
2331                 ublk_remove(ub);
2332
2333         class_destroy(ublk_chr_class);
2334         misc_deregister(&ublk_misc);
2335
2336         idr_destroy(&ublk_index_idr);
2337         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2338 }
2339
2340 module_init(ublk_init);
2341 module_exit(ublk_exit);
2342
2343 module_param(ublks_max, int, 0444);
2344 MODULE_PARM_DESC(ublks_max, "max number of ublk devices allowed to add(default: 64)");
2345
2346 MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>");
2347 MODULE_LICENSE("GPL");